Hydrocarbons are the source of many fuels and chemical feedstocks used for industry and commerce in the world. Petroleum is the predominant source of these hydrocarbons. This petroleum is sourced from geological deposits located beneath the surface of the earth. These hydrocarbons are then refined and reformed and used as source chemicals for fuels and feedstocks. Traditionally these hydrocarbons are sourced from geological resources. However, hydrocarbons can be found in most living organisms. As hydrocarbons are produced by living organisms, these organisms can be cultivated and processed for use as source hydrocarbons. The ideal organisms for use as petroleum substitutes use energy from the sun to fully reduce carbon dioxide into source hydrocarbons.
Higher plants produce hydrocarbon compounds composed primarily of isoprenoids, which are organic compounds comprised of two or more hydrocarbon subunits each having five carbon atoms. These isoprenoids are often in the form of hydrocarbon terpenes made from pentene subunits primarily comprised of 2-methyl-2-butene as well as 2-methyl-1-butene. Most plants produce these isoprenoid terpenes in small amounts and utilize them to form more complex biochemicals. However, some types of plants produce terpenes as a major metabolic product. In particular, some trees and shrubs of the Pinaceae, Myrtaceae, Styracaceae, and Burseraceae families have very high levels of hydrocarbons present within their tissues.
Prominent examples include pine and eucalyptus trees. From antiquity to early modern times, hydrocarbons removed from pines were used as tar for naval stores or turpentine for cleaning solvents. Myrtles generally yield more oxygenated and pleasant smelling hydrocarbons that are used in cough drops and vapor rubs containing Eucalyptus. In addition, styrax and myrrh tree species have been associated with resinous perfumes and incense since Biblical times.
Pine and eucalyptus trees contain particularly high levels of hydrocarbons having relatively low molecular weights. The hydrocarbons found in the woody tree material of these species are mainly comprised of oligomerized pentenes formed from isoprene-derived pentene subunits 2-methyl-2-butene and 2-methyl-1-butene. These pentenes are then constructed via cellular metabolism into other chemicals such as hormones, energy stores, or defense chemicals. These relatively low molecular weight oligomerized pentene metabolites are typically comprised of only a few monomers. Thus, the woody tree material from these species has the potential for economical production of a petroleum substitute.
Attempts in the prior art to produce a petroleum substitute from woody tree material have focused on enzyme and pyrolysis-based methods for breaking down a biomass of woody tree material to convert its energy into fuel feedstocks. Two main classes of fuel feedstocks have been produced: cellulosic ethanol and bio-crudes. Cellulosic ethanol has been derived from wood by breaking the cellulosic material down into simple sugars to be fermented by yeast or bacteria into ethanol. Bio-crudes have largely been produced by pyrolyzing woody tree material in order to break lignin and cellulose into smaller molecules. Bio-crudes generally have a very high oxygen content for a petroleum substitute due to the high oxygen content of cellulose and lignin in the woody biomass itself.
However, the prior art suffered from inefficiencies due to the energy costs required to achieve pyrolysis, the complexities of breaking down the woody tree material enzymatically, and the costs to derive the enzymes and provide an optimal environment required for processing the biomass into a fuel feedstock. In addition, the utilization of fuel feedstocks derived from woody tree material has been problematic as wood-derived feedstocks have significant chemical differences as compared to petroleum-derived feedstocks. Furthermore, converting wood into ethanol or bio-crude is a generally inefficient process that destroys and consumes the wood leaving little to no potential aftermarket for the processed biomass of wood.
Accordingly, a need exists in the art for a method of producing a petroleum substitute comprised of a hydrocarbon composition that can be produced from renewable woody tree-based sources in a simple and more economical manner than is currently achievable.